1. Field of the Invention
The present invention relates to a transfer apparatus that transfers a fine concavo-convex pattern formed on a surface of a mold to a surface of a workpiece using a lithography technique, and more particularly, to a transfer apparatus capable of reducing positional deviation (lateral deviation) between the mold and the workpiece.
2. Description of Related Art
In recent years, nanoimprint techniques have been researched and developed. According to the nanoimprint techniques, a quartz substrate is formed with a super-fine pattern by an electron drawing method or the like to form a mold (template, stamper), the mold is pressed against a resist film formed on a substrate surface as a workpiece under a predetermined pressure, thereby transferring the pattern formed on the mold (see non-patent document 1: Precision Engineering Journal of the International Societies for Precision Engineering and Nanotechnology).
When super-fine concavo-convex pattern formed on a mold such as a template and a stamper using the lithography technique is pressed against and transferred to a workpiece, it is necessary to precisely and finely adjust attitude of the mold with respect to a surface of the workpiece so that a transfer surface of the mold on which the pattern is formed and a surface of the workpiece come into intimate contact with each other equally and the fine concavo-convex pattern formed on the workpiece is precisely transferred to the workpiece.
To finely adjust the mold, the non-patent document 1 discloses a configuration in which a holding member for holding the mold is made of a flexible material, and when a transfer surface of the mold is pressed against the surface of the workpiece, the holding member of the mold is allowed to follow the surface of the workpiece along the surface of the workpiece.
When the attitude of the mold is finely adjusted such as to follow the surface of the workpiece, if the mold is pressed against the surface of the workpiece, it is necessary to press the mold under a pressure as small as possible so that the workpiece is not damaged, and the holding member of the mold is made based on a small pressure for controlling the attitude.
Therefore, in order to transfer the pattern formed on the transfer surface of the mold to the surface of the workpiece after the attitude of the mold with respect to the surface of the workpiece is finely adjusted, it is necessary to apply a large pressure. When the holding member of the mold is configured to cope with the attitude controlling small pressure, however, there is a problem that a large pressure required for transferring the pattern cannot be applied. There are various materials for workpieces depending upon use, and it is necessary to variously change the transfer the pressure when the pattern formed on the mold is to be transferred to the workpiece.
In the case of the transfer apparatus of this kind, it is necessary to strictly keep the parallelism of mutually contact surfaces of the mold and the workpiece, and to suppress the positional deviation (lateral deviation) in a direction perpendicular to the mutually pressing direction of the mold and the workpiece when the mold is pressed and released.
For this purpose, an apparatus described in Japanese Patent Application Laid-open No. 2004-34300 (patent document 1) is proposed. According to this apparatus, a lower horizontal portion of an L-shaped frame is provided with an X-Y stage, a workpiece supporting member is mounted on the stage, and an upper portion of a vertical portion of the frame is provided with a mold support portion through a vertical moving mechanism.
The workpiece support portion includes a support member (a workpiece support member) and a magnetic material provided thereon. A workpiece is set on the magnetic material. The support portion includes a support member which is vertically moved by a moving mechanism, and a magnet mounted on a lower surface of the support member through an elastic member. A mold is set on a lower surface of the magnet.
According to the conventional apparatus, deviation of parallelism is absorbed through the elastic member, and when the mold and the workpiece are pressed against each other, magnetic attraction force is applied between the support member which supports the mold and a support member which supports the workpiece by the magnet and the magnetic material, thereby preventing relative movement in a direction perpendicular to the pressing direction, i.e., the positional deviation (lateral deviation).
According to the apparatus disclosed in the patent document 1, when the mold is pressed against the workpiece by the magnetic attraction force caused by the magnet and the magnetic material, it is possible to suppress the positional deviation (lateral deviation), but if the mold is strongly pressed by the moving mechanism in addition to the magnetic attraction force, an upper portion of the vertical portion of the frame is warped leftward by the reaction force, and the positional deviation (lateral deviation) is generated. When the frame is deformed by temperature variation also, there is a problem that the positional deviation (lateral deviation) is generated.
When a mold is released from a workpiece, if ultrasound vibration is applied, it becomes easy to release the mold from the workpiece. However, when the amplitude of the ultrasound vibration is greater than the fine concavo-convex shape, it becomes easy to release the mold but there is a problem that the fine concavo-convex shape can be damaged and it is not always preferable to apply the ultrasound vibration.